Consider the Deccan traps

What could be more festive than learning something new about the probable cause of the extinction event that terminated the dinosaurs?

At least, it’s new to me, although according to Science Daily it’s been on the table for 30 years.

A definitive geological timeline shows that a series of massive volcanic explosions 66 million years ago spewed enormous amounts of climate-altering gases into the atmosphere immediately before and during the extinction event that claimed Earth’s non-avian dinosaurs, according to new research from Princeton University.

A primeval volcanic range in western India known as the Deccan Traps, which were once three times larger than France, began its main phase of eruptions roughly 250,000 years before the Cretaceous-Paleogene, or K-Pg, extinction event, the researchers report in the journal Science. For the next 750,000 years, the volcanoes unleashed more than 1.1 million cubic kilometers (264,000 cubic miles) of lava. The main phase of eruptions comprised about 80-90 percent of the total volume of the Deccan Traps’ lava flow and followed a substantially weaker first phase that began about 1 million years earlier.

The results support the idea that the Deccan Traps played a role in the K-Pg extinction, and challenge the dominant theory that a meteorite impact near present-day Chicxulub, Mexico, was the sole cause of the extinction. The researchers suggest that the Deccan Traps eruptions and the Chicxulub impact need to be considered together when studying and modeling the K-Pg extinction event.

Interesting, no? Not just the uninvited visitor from space, but also volcanic explosions right here on the blue dot.

The Deccan Traps’ part in the K-Pg extinction is consistent with the rest of Earth history, explained lead author Blair Schoene, a Princeton assistant professor of geosciences who specializes in geochronology. Four of the five largest extinction events in the last 500 million years coincided with large volcanic eruptions similar to the Deccan Traps. The K-Pg extinction is the only one that coincides with an asteroid impact, he said.

“The precedent is there in Earth history that significant climate change and biotic turnover can result from massive volcanic eruptions, and therefore the effect of the Deccan Traps on late-Cretaceous ecosystems should be considered,” Schoene said.

“Biotic turnover” – that’s such a nicely chilling phrase.


  1. says

    “Biotic turnover” – that’s such a nicely chilling phrase.

    Technically, a pineapple turnover cake is also a “biotic turnover” … But that doesn’t cheer me up.

  2. Al Dente says

    The K-T (Cretaceous-Tertiary) extinctions were worldwide, affecting all the major continents and oceans. Not only dinosaurs but also many plankton genera and tropical invertebrates as well as land plants went extinct. While the Chicxulub asteroid strike and its associated iridium deposits occurred during the K-T, there is reason to believe that the extinctions began before Chicxulub. The Deccan Traps volcanism combined with Chicxulub are strong contenders for the cause of the K-T extinctions.

  3. Lady Mondegreen (aka Stacy) says

    ‘Biotic turnover” is a chilling phrase.

    Nevertheless I think it would be a nice name for a dessert to compliment Primordial Soup.

  4. Lassi Hippeläinen says

    I’ve never liked the idea that a single meteor, essentially a Kronecker delta in the time scale of geology, could have caused a permanent change. Over the next few million years life should have returned back (or at least close) to what it had been.

    The meteor strike may have expedited matters, but the pressure for long term change must have come from elsewhere. The Deccan traps are a good candidate.

  5. chigau (違う) says

    I’ve had a few, so I think that “Lassi Hippeläinen” would be a good name for a heavy metal band.
    Merry Christmas 😉

  6. Karen Locke says

    A little bit of annoying housekeeping, in case anyone is confused: The Cretaceous-Tertiary (K-T) and Cretaceous-Paleogene (K-Pg) boundaries are the same thing. “Tertiary” is becoming an archaic term, The time period it describes (2.6 to 66 million years ago) is more commonly defined nowadays as two periods, Paleogene (23 to 66 million years ago) and Neogene (2.6 to 23 million years ago). Not sure of the thinking behind the change, but the shift to the new terminology has become pretty complete in the professional geology journals in the last decade.

  7. Trebuchet says

    You’ve gone and inspired me to go read up on flood basalts again. Especially since I’ll be driving through an area of them in central Washington tomorrow!

  8. AndrewN says

    I heard of the Deccan Traps a number of years ago and it has promise as an explanation for the K-T extinction event.

    Even better there is a geological feature called Siberian Traps that consists of an even larger volume of lava and happened at about the time of the P-T extinction event.

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